We have built a boat with a Pixhawk 2.4.8 and are now about to test the whole setup. The boat has two electric motors and two propellers that can be controlled independently. We used a generic ground vehicle and setup mixers to control the ESC’s. The boat performs very well and is capable to turn in place. Now we have one problem: After executing a “GoTo” command, the boat begins to navigate towards the waypoint, but suddenly stops before reaching it. The same problem occurs when we start a mission.
At the moment we have no single idea what could be the reason for this behavior. An
Example Log is available on Flight Review.
Any help is appreciated.
@stefanmessmer Awesome! Would you be able to share any pictures / videos of the setup?
The behavior of rover is that it stops at its last way point. This is to prevent the rover circling around at the last waypoint. Your issue sounds like the rover’s waypoint was reached within the acceptance radius(
NAV_ACC_RAD) and the boat stopped.
I think this makes more sense for the rover but maybe not for boats. What behavior would you consider to be more correct? Any suggestions would be helpful
I can also see that your boat went into altitude mode. Was this intended?
The problem we have at the moment is that NAV_ACC_RAD is set to 1.0 m and the boat stops 50 m (sometimes at 10 m or other distances) before the waypoint, but it is never correlated to the NAV_ACC_RAD. We also have set GND_L1_DIST to 1 m, but we never reached the state to observe the behavior around a waypoint. Any help on this point is appreciated.
You are right, boats are quite different from rovers. Due to wind and currents a boat will drift away from its position as soon as the motors stop. But this is a minor problem at the moment.
The switch to altitude mode was intended (at the moment), because we did not manage to configure the RC otherwise.
Pictures or videos follow as soon we have time to shoot them.
@stefanmessmer Okay thanks, is this something reproducible in SITL?
If it is, it would be helpful if you could provide instructions on how to reproduce the problem.
After studying the parameters (and its values) we decided to modify NAV_LOITER_RAD to 1m. This seems to solve the problem. The boat stops now at the desired point. Mission seems to work also, but we have to fine tune some other parameters to avoid extra loops.